How Solar Storms Affect Satellites

The Four Threats

Space weather affects satellites through four primary mechanisms. Each poses distinct risks depending on the satellite's altitude, orbit, design and shielding. Understanding these threats is essential for operators, insurers and anyone monitoring the health of the orbital environment.

1. Atmospheric Drag Enhancement

This is the most significant space weather threat to satellites in low Earth orbit (LEO). During a geomagnetic storm, energy deposited in Earth's upper atmosphere by auroral currents and particle precipitation heats the thermosphere, causing it to expand. Neutral gas density at typical LEO altitudes (300–600 km) can increase by a factor of 2–10 during a major storm, sometimes even more.

The result is a dramatic, sudden increase in aerodynamic drag on every object in LEO. Satellites lose altitude faster, their orbital decay accelerates, and if they cannot raise their orbits quickly enough, they may re-enter the atmosphere prematurely. Even for satellites that survive, the unexpected drag changes cause their TLE-predicted positions to diverge from reality, temporarily degrading tracking accuracy.

Case Study: Starlink Storm Loss — February 2022

On 3 February 2022, SpaceX launched 49 Starlink satellites on the Falcon 9 mission Group 4-7. The satellites were deployed into a low initial orbit of approximately 210 km altitude — standard practice for Starlink, which uses this low insertion orbit as a "checkout" altitude before the satellites raise themselves to their operational orbit of ~550 km using onboard ion thrusters.

Unfortunately, a moderate G1–G2 geomagnetic storm struck on 4 February. The storm increased atmospheric drag at 210 km by up to 50% compared to previous launches. At this very low altitude, the satellites' ion thrusters could not generate enough thrust to overcome the increased drag. Up to 40 of the 49 satellites were unable to climb out and re-entered the atmosphere over the following days and weeks.

The event was a watershed moment for the industry. It demonstrated that even a modest geomagnetic storm — far from a worst-case scenario — could cause significant satellite losses if timing and altitude aligned unfavourably. SpaceX subsequently adjusted its deployment procedures, and the event prompted wider industry discussion about space weather risk in constellation operations.

2. Radiation Damage

Solar energetic particle (SEP) events and trapped radiation belt particles can damage satellite hardware in several ways:

• Total ionising dose (TID) — cumulative radiation exposure degrades semiconductor devices over the satellite's lifetime, particularly solar cells. Solar panel output typically decreases by 1–3% per year under normal conditions, but a major SEP event can accelerate this significantly.
• Single-event effects (SEEs) — a single high-energy particle striking a transistor can flip a memory bit (single-event upset / SEU), trigger parasitic currents (latch-up) or even permanently destroy a component (single-event burnout). SEUs are the most common; they're typically correctable through error-correction codes, but latch-ups and burnouts can be fatal.
• Displacement damage — energetic protons displace atoms in crystal lattices, degrading solar cells and optical sensors. This is a particular concern for Earth-observation and astronomical satellites.

Satellites in geostationary orbit (GEO) and medium Earth orbit (MEO) are most exposed to radiation because they spend time in or near the Van Allen radiation belts. LEO satellites below the inner belt (~1,000 km) receive lower doses, except when passing through the South Atlantic Anomaly (SAA) — a region where the inner radiation belt dips closer to Earth's surface. Many satellites automatically enter a "safe mode" when transiting the SAA.

3. Spacecraft Charging

During geomagnetic storms, hot plasma injected into the magnetosphere can accumulate on spacecraft surfaces, creating voltage differentials of hundreds or even thousands of volts. There are two types:

• Surface charging — differential charging between sunlit and shadowed surfaces can cause electrostatic discharges (arcs) that damage coatings, sensors and electronics. This is primarily a threat to GEO satellites, where plasma temperatures are higher.
• Internal (deep dielectric) charging — high-energy electrons penetrate spacecraft shielding and accumulate in insulating materials inside the satellite, eventually discharging and damaging internal circuits. This is driven by sustained high-speed solar wind streams and can build up over days.

Spacecraft charging has been implicated in numerous satellite anomalies and several total losses. The Anik E-1 and E-2 communications satellites both suffered charging-related failures during the January 1994 geomagnetic storm, and Telstar 401 was lost to an apparent charging event in January 1997.

4. Tracking and Communication Disruption

Space weather can degrade the systems used to track and communicate with satellites:

• Radar degradation — ionospheric disturbances during storms can refract and attenuate radar signals used by the Space Surveillance Network, temporarily reducing tracking accuracy and catalogue maintenance.
• HF radio blackouts — solar flares ionise the D-region of the ionosphere, absorbing HF radio signals. This can disrupt communications with aircraft, ships and some ground stations for minutes to hours.
• GPS/GNSS errors — ionospheric scintillation and total electron content (TEC) variations degrade positioning accuracy, affecting both ground users and satellites that rely on GNSS for orbit determination. See our Space Weather & GPS guide.

Satellite Vulnerabilities by Orbit

Mitigation Strategies

Satellite designers and operators use several approaches to reduce space weather risk. Radiation-hardened electronics are standard for military and GEO missions, though they add cost and mass. Constellation operators like SpaceX build in redundancy — losing a handful of satellites to a storm is acceptable when the constellation has thousands. Operators monitor NOAA SWPC forecasts and can place satellites in safe mode before a predicted event, reducing the risk of charging-related anomalies. Some LEO operators pre-emptively raise satellite altitudes ahead of forecast storms to increase their drag margin.

For the tracking community, understanding that TLE accuracy degrades during storms is important. If you notice satellites on Orbital Radar drifting from their predicted tracks during a geomagnetic event, increased atmospheric drag is the most likely explanation — the satellites are still there, but the orbital models haven't caught up yet.